One of the busiest travel days of the year got off to a rough start due to a "technical issue" that disrupted American Airlines flights across the U.S.The Federal Aviation Administration said early Tuesday that American Airlines requested a ground stop for all of its flights nationwide as millions hit the skies ahead of the Christmas holiday. A short time later, the agency announced that the nationwide ground stop had been canceled.This comes after numerous American Airlines passengers were posting on social media that their flights had been stopped on runways at various airports and were returning to their gates.RELATED STORY | American Airlines suspends flights to Haiti indefinitely"We're currently experiencing a technical issue with all American Airlines Flights," the airline replied back to one person on social media. "Your safety is our utmost priority, once this is rectified, we'll have you safely on your way to your destination."American Airlines didn't elaborate on what what caused the technical issue.The grounding comes just months after a global tech outage sent airlines and other institutions into mayhem. The Cybersecurity firm CrowdStrike later said a bug in a software update caused the disruptions.This is a developing news story and will be updated as more information becomes available. Check back for updates.